Tartarus - Court between Olympus and Hades. My own vision fo Tartarus. In Greek mythology is a deep, gloomy place, a pit, or an abyss used as a dungeon of torment and suffering that resides beneath the underworld, but I refer to Christian faith.
Olympus is pretending Heaven, Hades is pretending eternal torment and Tartarus is Purgatory ...
MOC for Mini Castle Contest on Classic-Castle, organized by wobnam. My thanks for him :).